Data storage devices include heads to read digitally encoded information from a disc or data storage medium and/or write digitally encoded information to the disc or data storage medium. Heads are typically coupled to an actuator or E-block to form a head stack assembly including a plurality of heads to read information from or write information to a plurality of discs of a disc stack. The plurality of heads of the head stack assembly are merged with the plurality of discs of the disc stack to read data from and/or write data to the plurality of discs of the disc stack.
Heads are coupled to the E-block or actuator via a plurality of suspension assemblies or suspension arms. Typically, the head includes an air bearing slider to provide a dynamic fly height (along a z-axis) for the head above the disc surface. The head or slider is coupled to the suspension assembly or suspension arm via a gimbal spring or gimbal device to allow the head or slider to pitch and roll relative to a load point of the suspension assembly to follow the topography of the disc surface. The head and gimbal spring collectively form a head gimbal assembly and the head and suspension collectively form a head suspension assembly.
Manufacturing tolerance variations can introduce variations to static dimensions of the suspension assembly and head. For example manufacturing tolerance variations can introduce variations to pitch static attitude (PSA), roll static attitude (RSA) or z-height parameters of the head or slider. PSA and RSA can vary based upon variations in flexure or relative stiffness of suspension components. Variations in PSA and RSA parameters can affect pitch, roll and z-height parameters of the head or slider relative to the disc surface and fly height parameters for read or write operations of the data storage device.
To control manufacturing tolerance variations, static dimensions, such as PSA and RSA are measured. For measurement, a head stack comb assembly is used to hold suspension arms relative to a static measurement position corresponding to an elevational or z-height of the head or suspension assembly after loaded or merged with a disc. Head stack combs include a plurality of teeth having a thickness dimension sized to hold the suspension arms relative to the static measurement position of the head or assembly. Accuracy of the thickness dimension of the teeth and position and elevation thereof is important for accurate measurement.
For example, static measurements can vary depending upon the height at which the suspension arm is held by the teeth of the comb. Determining optimum dimensions of the comb and thickness of the comb teeth is difficult. Manufacturing a variety of combs having different tooth dimensions and parameters can be tedious and expensive. The present invention addresses these and other problems and offers solutions not previously recognized nor appreciated.